1. Technical Field
The present invention relates to a liquid discharging apparatus.
2. Related Art
A liquid discharging apparatus such as an ink jet printer that forms an image on a medium by discharging ink from a discharging unit may experience an abnormal discharge that means ink cannot be normally discharged from the discharging unit due to thickening of ink, mingling of air bubbles with ink, and the like. An abnormal discharge occurring in the discharging unit prevents accurate formation of a dot that is supposed to be formed by ink discharged from the discharging unit and thus decreases quality of the image formed on the medium. In order to prevent such a decrease in image quality due to an abnormal discharge, a technology is suggested in which an abnormal discharge is detected by determining a state of discharge of ink from the discharging unit (for example, JP-A-2004-276544).
It is preferable to detect an abnormal discharge promptly so as to prevent a decrease in image quality due to an abnormal discharge. An abnormal discharge is caused by various events depending on a status of use of the liquid discharging apparatus, such as thickening of ink due to long-term non-use of the liquid discharging apparatus, mingling of air bubbles during printing, temporal degradation of the discharging unit, and physical failure of the discharging unit due to vibrations occurring in the discharging unit when liquid is discharged from the discharging unit. Thus, in order to detect an abnormal discharge promptly, a determination of the state of discharge in the discharging unit is required to be flexibly performed depending on the status of use of the liquid discharging apparatus, such as not only when the liquid discharging apparatus is booted but also when a printing process of forming an image on the medium is performed or after the printing process is performed.
However, as in the technology disclosed in JP-A-2004-276544, a determination of the state of discharge may be performed in limited cases due to temporal restrictions when a determination of the state of discharge is performed on all discharging units provided in the liquid discharging apparatus. In this case, detection of an abnormal discharge is delayed, and the possibility of forming a low-quality image is increased.